1. Field of the Invention
The present invention relates generally to an apparatus for providing a visual indication of a current location of a mobile craft. More particularly, the invention relates to an improved apparatus having a visual indication function of a current location of an automotive vehicle or the like, for providing a visual display of combined information on a current travel status of the vehicle, such as in terms of a current location, a path of travel, a travel direction, etc., for the driver or operator.
2. Description of Relevant Art
In order to prevent the driver or operator of an automative vehicle or the like from becoming lost when driving at night or in unfamiliar surroundings away from his desired route of travel, there have been proposed a variety of apparatus which are specifically designed to provide the driver with suitable ready guidance relating to the vehicle's current status of travel with reference to the desired course of travel from time to time during travel, by indicating continuously or discretely a due current position or similar information on the vehicle by way of an indication panel or display screen including a related road map or the like disposed at the driver's seat.
In a typical conventional apparatus for visually indicating a current location of an automotive vehicle for use in such application, a current travel distance of a vehicle is detected by way of distance detecting means in accordance with its current travel speed and time of travel, a current bearing and a current quantity of azimuthal deviation of the vehicle are detected by bearing detecting means, and a current location of the vehicle along its travel route is obtained from arithmetical operation on the basis of the thus-obtained route detection data. The result of such arithmetic operation is stored for visual indication on a display in the form of spot information, which varies from time to time during travel of the vehicle, on a display screen on which there is placed in advance a suitable road map such as printed on a transparent sheet or the like. The driver may thereby comparatively review the thus-indicated visual information and the geographical indication by way of the map sheet so that he may visually confirm the current location of the vehicle along its travel route.
With such a typical construction of the apparatus for use as described hereinabove, however, it is commonly required in order to obtain a due locational guidance with reference to the current location of an automotive vehicle that the driver of a vehicle must take the trouble to select in advance of travel one proper sheet from a plurality of prepared local maps which includes a correct area of travel, so that it may be placed in position on the surface of the display. The driver must also manually adjust such map sheet set upon the display screen because it is likely to randomly shift out of its due position during travel of the vehicle due to vibrations, turning motion, etc., which may be frequently encountered during the vehicle's travel. These operations are awkward and troublesome for the driver or operator.
The present invention effectively overcomes the aforesaid inconveniences and difficulties experienced in selecting from a set of local area maps as printed on transparent sheets so as to be set upon the display screen in the conventional location detecting apparatus for use in an automotive vehicle.